1. Field of the Invention
The present invention relates to nonwoven elastomeric webs and to elastomeric adhesive and cohesive materials which are useful as wound dressing or bandaging materials.
2. Background Information
Dressings and tapes applied to the skin should preferably exhibit a degree of stretchiness so that they do not unduly restrict movement of the underlying skin. This is particularly important in skin areas such as fingers, elbows and knees which are subjected to continuous stretching and relaxation during normal activities. If a tape does not exhibit elastic properties similar to or greater than skin, the tape will exert a force against the skin causing discomfort and in some cases, actual damage to the skin.
Cohesive, self-adhesive compression and support bandages applied to limbs of the body are required to be elastic to provide variable tensions dependent on application and compensate for edemic conditions. After being wrapped on a limb some elasticity should remain in the bandage to allow for subsequent edema in the limb and the bandage should have sufficient elastic recovery to return to substantially the extensibility at application after the edema subsides.
U.S. Pat. No. 3,575,782 (Hansen) discloses an elastic shirred web product which consists of partially extended spaced aligned elastic yarns sealed between two thin porous gathered non-woven fibrous webs, or between a web and a non-porous film, by means of a soft flexible polymeric coherent binder.
U.S. Pat. No. 4,366,814 (Riedel) discloses an elastic bandage material for medical tapes and dressing which has at least 50 percent by weight of an extensible porous fabric capable of elongation of at least 30 percent in one direction without tearing and at least 15 percent by weight of an elastomer uniformly impregnated in the fabric and substantially contained on or within the fibers of the fabric without filling the spaces between fibers. The fabric may be of a wide range of synthetic or natural fibers, used singly or in blends. The preferred elastomers include block copolymers, polyurethanes, acrylics, acrylic-olefinic copolymers, and other natural and synthetic rubbers.
U.S. Pat. No. 4,414,970 (Berry) discloses a moisture vapor transmitting elastic bandage which has an inner layer of fabric and an outer layer of fabric bonded to a central layer which is an elastomeric film. The film can be continuous, macroporous or microporous, but is preferably continuous to provide a bacterial barrier. Suitable films which may be obtained in continuous form and which transmit moisture vapor can be made from polyurethane, for example, a thermoplastic polyurethane.
U.S. Pat. No. 4,565,736 (Stein et al.) discloses a surgical compress which is made of an absorptive layer and a wound covering layer, the covering layer spun or otherwise made of nonwoven hydrophobic, hydrolysis-resistant, aliphatic polyurethane fibers, the covering layer preferably being autogenously bonded to the absorption layer by direct formation of tacky cover layer fibers on the absorption layer.
U.S. Pat. No. 4,715,857 (Juhasz et al.) disclose wound dressings which comprise, in order, a first layer of a permeable material, a layer of a semi-permeable, adhesive material, a charcoal cloth or felt, and a second layer of a permeable material, in which the three layers are substantially co-extensive and surround the charcoal cloth or felt, whereby the first layer of permeable material is bound to the cloth or felt and, around the cloth or felt, to the second layer of permeable material. The layers of permeable material are in the form of a fabric or film and may be of different or, preferably, the same material, examples of suitable materials being natural or synthetic rubber, nylon, polyester, polyurethane and rayon acetate, and other suitable synthetic polymers. The semi-permeable adhesive materials are preferably double-sided transfer tapes.
U.S. Pat. No. 4,653,492 (Parsons) discloses an elastic bandage having a resilient elastic layer and a relatively non-resilient layer. The elastic layer has sufficient resiliency so as to apply a compressive force to a body extremity when wrapped around the body extremity and the relatively non-resilient layer which has either less resiliency than the elastic layer or relatively little resiliency or no resiliency limits the stretching of the layer of elastic material so that an inexperienced person can apply the elastic bandage without fear of applying it too tightly or too loosely.
U.S. Pat. No. 4,699,133 (Schafer et al.) discloses a cohesive, self-adhesive, rigid or elastic bandage for fixing, compression and support dressings and permanent elastic compression and support dressings for medical purposes. The bandage comprises a web of warp and weft threads or warp threads in the form of a woven fabric having a porous structure and an amount of ultra fine particles of an adhesive, such as a rubber adhesive distributed over and bonded to both the exposed surfaces of the warp and weft threads to provide adhesive particles bonded to the threads on both sides of the fabric.
British Patent Specification 1,575,830 (Johnson & Johnson) discloses a flexible and conformable disposable absorbent dressing which comprises a layer of absorbent material, and a thin, flexible, elastic and easily stretchable thermoplastic backing film retained in superimposed relationship with the absorbent layer, the backing film possessing an elastic recovery from 50 percent stretch of at least 75 percent, a rubber modulus of not above 2000 pounds per square inch and a Gurley stiffness at a thickness of 1 mil of not above one. The film is preferably formed from A-B-A block copolymers which consist of A end blocks derived from styrene and B blocks derived from conjugated dienes.
Ogawa, in an article entitled "Development of Spunbonded Based on Thermoplastic Polyurethane," Nonwovens World, May-June, 1986. pp 79-81, describes a spunbonded nonwoven polyurethane elastic fabric developed by Kanebo Ltd. The fabric is made using a melt blown process which is different from a conventional melt blown process to produce fabric which is similar to that of spunbonded fabrics. The diameter of its filaments is not so fine as that of the usual melt blown fabrics, i.e., 0.5-2 mm, but apparently is closer to that of the spunbonded fabrics, i.e., 20-50 mm. The elasticity, dust catching capability, low linting, high friction coefficient, air permeability and welding characteristics of the urethane fabrics are discussed in the article.